Scientists Get into the Flow at the Complex Fluids Workshop

By Anne-Marie Kent

If you push on a liquid-crystal display, its hidden liquidity becomes apparent: digital numbers, once touched, distort into puddles of fingerprint form. UMass Boston physicist Greg Huber says all fluids reveal this kind of mechanical softness, a sensitive, "almost lifelike" response to varying conditions.

From liquid-crystal displays to detergents, soaps, and petroleum products, even fluids we drink such as milk, we're surrounded by complex fluids. "Water is what the average person would point to as the ideal 'fluid,' but in fact a lot of everyday life involves fluids with far different properties, or in much more complex states than a simple glass of water," explains Huber, assistant professor of physics. "The everyday world presents such a multifarious variety and multiplicity of fluid-like materials and behavior that no simple definition encompasses all the phenomena, but, nonetheless, researchers have settled on 'complex fluids' as a catchall phrase," says Huber.

On March 21, more than 80 scientists fascinated by the properties of complex fluids came to UMass Boston for the 14th New England Complex Fluids (NECF) Workshop. They came from universities throughout the country, including Cornell, Brown, Harvard, Yale, and MIT, to attend the event, which Huber brought to this campus.

"When I arrived at UMass Boston a couple years ago, I discovered that many area physicists had absolutely no idea there even was a UMass in Boston. Clearly, the invisibility of the Physics Department here had to change, but how to go about doing this was not clear," says Huber. "Enter the NECF workshops. They were initiated by Seth Fraden from Brandeis and Dave Weitz from Harvard some years ago, and have traditionally oscillated between those universities. It seemed like a good opportunity for our Physics Department to engage with the greater Boston research community."

The program included five invited talks, entitled "Mechanics of Bacterial Flagella," "Self-Assembling Biological Springs," "Collective Phenomena in Intracellular Networks," "Probing Polymerization Forces Using Actin-Propelled Lipid Vesicles," and "Force Spectroscopy of Single Molecule DNA-Protein Interactions." In addition, there were 29 brief contributed talks, including three presented by UMass Boston graduate students.

One presentation even addressed qualities of slime molds. "Why would anyone care about slime molds?" Huber was asked. "Because they are eukaryotes, slime molds are our close relatives on the tree of life, and they have been much studied as a model organism. Nonetheless, it is not even understood exactly how they are able to move about in response to chemical clues in their environment."

Huber explains, "Many people go into this just for the sake of curiosity. They just want to know how single molecules, especially huge ones like DNA or proteins, behave. Curiosity drives this field, and applications are the by-product."

He adds, "Production, manipulation, and control of complex fluids are major issues for industry. A significant proportion of chemical engineers, for instance, rely on the robust connections between industrial practices and research work on complex fluids."

And there's room for more discovery. "Many of the technological advances of recent years have resulted from making circuits smaller or exploiting new phenomena at the micron scale or below," says Huber. "Most of these are built on advances in hard condensed matter physics. We are just beginning to see what structures can be based on soft matter physics. Life has already figured this out: cells work at this scale, and evolution has devised for them incredible structures, devices, and machines that we can only marvel at. We don't know how they work or how to build them from scratch," says Huber.

Image: More than 80 scientists attended the 14th Annual New England Complex Fluids Workshop held at UMass Boston this year, including (from left to right): Darren Link and Peter Schall from Harvard University and Edw Ginsberg of UMass Boston's Department of Physics. (Photo by Karen Silverstein, FOOW Films)

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